The1H-NMR spectra of liquid binary mixtures, acetonitryle (ACN) - water (H2O), were recorded at 298 K and the spectral parameters, ΔΔ(ACN-H2O) were evaluated. The surface tensions (σ12) were measured at 298.15 K. From literature values of density (d12), viscosity (η12), relative permittivities (ϵ12) and measured surface tensions the values of molar volumes (V12) and their deviations from “ideality” were calculated. Further on the temperature coefficients of relative permittivity, α2=(1/ϵ12).[dϵ12/d(1/T)], were evaluated. These structural parameters as functions of concentration suggest the formation of the intermolecular “complexes” of the ACN • 2H2O, ACN • H2O, 2 ACN • 3H2O and 2 ACN • 3 H2O types.